The present invention relates to paper handling. Select embodiments of the invention are particularly well-suited for use in the waste paper recycling industry.
Environmental campaigns and recycling in many offices have generated a supply of recyclable waste paper. However, waste paper sorting is still currently performed almost entirely by manual sorting. This is time consuming and expensive. Thus, heretofore it has generally been more economical to use raw paper material than sort and process recyclable waste paper.
Numerous automated waste separation techniques are known. However these systems are designed for recovery of non-ferrous metals, aerospace alloys, municipal waste, mixed recyclables and plastic containers. Paper sorting presents unique problems not overcome by prior art separation techniques.
The unique problems encountered when attempting to sort waste paper is due to the relatively light weight and flexible nature of pieces of paper. These characteristics make it difficult to supply paper to a sorting sensor. Even when waste paper has been supplied to a sensor, it has not been supplied at a sufficient feed rate, e.g. pieces per hour (PPH), to be cost effective. Prior art sensors operate on the basis of an eddy current created by the waste stream as it passes through the sensor, diffusion of light transmission through the waste e.g. transparent glass, and the like. These techniques are inapplicable to sorting waste paper because the paper has no metallic components and the paper is opaque to light. Thus, not only must an effective paper sorting sensor be designed, an effective paper handling system must be designed to supply waste paper in sufficient feed rates to the effective paper sorting sensor. Prior art paper handling techniques have been unsatisfactory in overcoming these obstacles.